This invention relates to apparatus for the examination and surgery of both the anterior portions and the posterior portions of the eye.
For examination and operative therapy in the anterior portion of the eye, there have been available for a long time operation microscopes providing stereoscopic observation and which permit paraxial illumination with the instrument and oblique illumination by means of fiber optics or by slit illumination, and which are equipped with a pancratic variation of magnification as well as with connecting means for a co-worker's microscope and for documentary apparatus.
An observation microscope for several observers which has a pancratic system in the observation ray path is described in Fed. Rep. Germany patent No. 29 49 428 and in the corresponding U.S. Pat. No. 4,341,435 of Lang et al., granted July 27, 1982. An optical system of variable back focus and focal length which can be combined with the main objective of an operation microscope is disclosed in Fed. Rep. Germany Offenlegungsschrift (published but unexamined patent application) No. 32 02 075 A1 and in the corresponding European patent No. 0 085 308 and U.S. Pat. No. 4,525,042 of Muchel, granted June 25, 1985. The illumination ray path in an operation microscope is illustrated on page 222 of the English-language book "Handbook of Ophthalmic Optics," published 1983 by the Carl Zeiss firm of Oberkochen, West Germany, and on page 223 of the German-language edition of this book, published 1977 by the Zeiss firm under the title "Handbuch fur Augenoptik."
For the examination of the posterior region or fundus of the eye, ophthalmoscopes are known which make it possible, by direct or indirect observation, to illuminate and observe the retina of the eye, through the pupil, by means of mirrors or prisms. Such ophthalmoscopes are known, for instance, from pages 216 and 217 of the English-language edition of the above-mentioned Handbook.